The present invention relates to an optical disk apparatus and, more particularly, to an optical disk apparatus capable of recording data on an optical disk medium using a plurality of laser beams.
In a conventional optical disk apparatus, data are recorded on an optical disk medium by irradiating the optical disk medium with a beam. In this case, data are recorded on the optical disk medium using changes in shape of those portions of the optical disk medium which are heated by irradiation of the optical disk medium with a beam, the direction of magnetic fields aligned under the influence of an external magnetic field when a high temperature decreases to room temperature, and changes in crystalline state caused by the temperature difference between a high temperature and room temperature.
In an optical disk apparatus of this type, when the servo becomes unstable during recording/erase of data on/from an optical disk medium, the recording/erase immediately stops in order to protect user data near portions where data are to be recorded/erased. Also, when an abnormal portion is detected on an optical disk medium, recording/erase immediately stops.
The above optical disk apparatus is constructed by a recording head 319 and an erase head 320, as shown in FIG. 5. The recording head 319 is constituted by a semiconductor laser 301, a laser driver 302, a protective circuit 303, a recording data generator 304, a photodetector 305, a medium reflection signal generator 306, a recording abnormality detector 307, a reproducing circuit 308, and an abnormal sector memory 309.
The erase head 320 is constituted by a semiconductor laser 310, a laser driver 311, a protective circuit 312, an erase data generator 313, a photodetector 314, a medium reflection signal generator 315, an erase abnormality detector 316, a reproducing circuit 317, and an abnormal sector memory 318.
When data are simultaneously recorded and erased with a plurality of heads, they are substantially simultaneously recorded by the recording head 319 and erased by the erase head 320 at the same portion of a recording medium 321 on the same track.
A signal obtained from the recording data generator 304 is transmitted to the laser driver 302 via the protective circuit 303. On the basis of the recording signal transmitted via the protective circuit 303, the laser driver 302 records data on the recording medium 321 using the semiconductor laser 301.
A signal obtained from the erase data generator 313 is transmitted to the laser driver 311 via the protective circuit 312. On the basis of the erase signal transmitted via the protective circuit 312, the laser driver 311 records erase data on the recording medium 321 using the semiconductor laser 310 to erase data from the recording medium 321.
In recording, a signal obtained via the photodetector 305 is converted into a medium reflection signal by the medium reflection signal generator 306. The medium reflection signal is transmitted to the recording abnormality detector 307. The recording abnormality detector 307 detects based on the medium reflection signal whether focusing control and tracking control fall within normal ranges, and the medium is free from any defect.
A recording abnormality detection signal detected by the recording abnormality detector 307 is transmitted to the protective circuit 303 and the abnormal sector memory 309, and in addition, to the protective circuit 312 and abnormal sector memory 318 of the erase head 320. Upon reception of the recording abnormality detection signal, the protective circuit 303 immediately stops transmission of recording data to the laser driver 302. In the abnormal sector memory 309, a sector detected to have a recording abnormality is stored on the basis of signals obtained from the reproducing circuit 308 and the recording abnormality detector 307.
In the erase head 320, the protective circuit 312 immediately stops transmission of erase data to the laser driver 311 upon reception of the recording abnormality detection signal. In the abnormal sector memory 318, a sector subjected to forcible stop due to the recording abnormality is stored on the basis of signals obtained from the reproducing circuit 317 and the recording abnormality detector 307. The abnormal recording sector and the abnormal erase sector obtained from the abnormal sector memories 309 and 318 are subjected to recording and erase retries or swapping of recording data on other sectors.
In erase, a signal obtained via the photodetector 314 is converted into a medium reflection signal by the medium reflection signal generator 315. The medium reflection signal is transmitted to the erase abnormality detector 316. The recording abnormality detector 316 detects based on the medium reflection signal whether focusing control and tracking control fall within normal ranges, and the medium is free from any defect.
An erase abnormality detection signal detected by the erase abnormality detector 316 is transmitted to the protective circuit 312 and the abnormal sector memory 318, and in addition, to the protective circuit 303 and abnormal sector memory 309 of the recording head 319. Upon reception of the erase abnormality detection signal, the protective circuit 312 immediately stops transmission of erase data to the laser driver 311. In the abnormal sector memory 318, a sector detected to have an erase abnormality is stored on the basis of signals obtained from the reproducing circuit 317 and the erase abnormality detector 316.
In the recording head 319, the protective circuit 303 immediately stops transmission of recording data to the laser driver 302 upon reception of the erase abnormality detection signal. In the abnormal sector memory 309, a sector subjected to forcible stop due to the erase abnormality is stored on the basis of signals obtained from the reproducing circuit 308 and the erase abnormality detector 316. The abnormal recording sector and the abnormal erase sector obtained from the abnormal sector memories 309 and 318 are subjected to recording and erase retries or swapping of recording data on other sectors.
In the conventional optical disk apparatus described above, if the recording abnormality detector 307 or the erase abnormality detector 316 detects an abnormality, the other circuit (erase head 320 or recording head 319) is also informed of this abnormality, and erase or recording in the other circuit is forcibly stopped.
For this reason, a sector, which may normally undergo recording or erase, is processed as an abnormal sector by an abnormal stop signal from one head. As a result, the recording and erase times of the optical disk apparatus are prolonged.
The above operation will be explained on the time axis shown in FIGS. 2A to 2D, 2G, and 2H. FIGS. 2A to 2D, 2G, and 2H show the case wherein the recording head 319 records data on recording sectors 200 "X, X+1, X+2, . . . ", and the recording head 320 erases data from erase sectors 203 "Y, Y+1, Y+2, . . . ", as shown in FIG. 2D.
When a recording abnormality occurs in the recording sector 200 "X+1" (FIG. 2A), and an abnormality signal 201 (FIG. 2B) is output upon detection of the recording abnormality, an abnormal recording stop signal 202 (FIG. 2C) is input to the protective circuit 303 to stop current recording. "X+1" is stored as an abnormal recording sector in the abnormal sector memory 309.
At the same time, on the erase head 320 side, the abnormal recording stop signal 202 (FIG. 2C) input to the protective circuit 312 immediately stops current erase. "Y+1" is stored as an abnormal erase sector in the abnormal sector memory 318. As for the erase sector, no recording abnormality occurs in the sector "Y+1", but only the abnormal recording stop signal 202 (FIG. 2C) is input from the recording head 319. Processing for the sector "Y+1", which may normally end, abnormally stops a time T1 before the end, and thus "Y+1" is recorded as an abnormal sector.
When an erase abnormality occurs in the erase sector 203 "Y+4" (FIG. 2D), and an abnormality signal 206 (FIG. 2G) is output upon detection of the erase abnormality, an abnormal erase stop signal 207 (FIG. 2H) is input to the protective circuit 312 to stop current erase. "Y+4" is stored as an abnormal erase sector in the abnormal sector memory 318.
At the same time, on the recording head 319 side, the abnormal erase stop signal 207 (FIG. 2H) input to the protective circuit 303 immediately stops current recording. "X+4" is stored as an abnormal recording sector in the abnormal sector memory 309. As for the recording sector, no erase abnormality occurs in the sector "X+4", but only the abnormal erase stop signal 207 is input from the erase head. Processing for the sector "X+4", which may normally end, abnormally stops a time T2 before the end, and thus "X+4" is recorded as an abnormal sector.